Amplifiers with a "warm" sound are colored, either intentional, poorly designed, or defective. If you are looking for an amplifier like this, then this might be the wrong forum for it. Many tube amplifiers, but also so-called audiophile amplifiers, such as a Musical Fidelity A1, produce such a sound image.
Maybe this thread is interesting for you:
Got a Chinese tube amp and now world is upside down
Since the sound differences are small to marginal, the most important thing when choosing is functionality. Remote control, connections, subwoofer output, digital inputs, Bluetooth, HDMI (e)ARC, etc. An SMSL AO300, for example, has a very high-quality DAC with USB, Toslink, Coax, HDMI ARC, Bluetooth, headphone amplifier, etc.
You will find many very good and cheap amplifiers in Amirm reviews.
You can take a look at SMSL, A50, A100, A300, AO100, AO200, AO300, AL200. Yamaha A-S200/300/500/700, R-S202, Fossi V3 etc. There is currently an unbeatable offer for the Sabaj A5 on Amazon (de).
If you have a higher budget, you can also look at SMSL VMV A1, Sabaj A30a or many of Audiophonics' in-house amplifiers.